Aug. 9 (Bloomberg) — The Democratic presidential candidates will debate gay and lesbian issues tonight in Los Angeles. That's a waste, because they still haven't settled another vital topic: Barack Obama's willingness to talk to tyrants, and Hillary Clinton's objection to that idea.

Obama has been upfront about meeting with all leaders. "The notion that I was somehow going to be inviting them over for tea next week without having initial envoys meet is ridiculous," the senator from Illinois told a reporter. "But the general principle is one that I think Senator Clinton is wrong on, and that is if we are laying out preconditions that prevent us from speaking frankly to these folks then we are continuing the Bush-Cheney policies."

Hail Hillary. Here is one case where Mrs. Clinton is completely in the right. Indeed, the phrase she used to characterize Obama on this — "irresponsible and naïve" — probably did more for her campaign than any other three words she has spoken.

But another question is why it is Clinton who uttered these words, and not Obama. The answer has to do not with where each of the two sits on the Democratic political spectrum. Hillary's conviction probably comes out of the 1990s. In those years, she was living in the White House and watched Yasser Arafat slowly make a fool of President Bill Clinton by ignoring the Oslo Accords. This was how the Clintons lost their naivety.

Starting From Zero

Call it the "tyrant learning curve." Out of vanity and a sense of fairness, most American leaders start out their jobs about where Obama is — at zero. As the foreign leaders they meet with betray them, they gradually get more cautious.

Of course, the evidence of that betrayal isn't always available before they leave office. And their experience has scant use in any case, for it only accrues to something significant around the time when the next guy is ready to take over — and start the trip up the curve all over again.

Consider the history. President Harry Truman, new in office as World War II was ending, probably had the steepest curve.

He wanted to find someone he could work with in Josef Stalin, and at first, in 1945, he thought he did: "I like Stalin," Truman wrote to Bess, his wife, after the summit at Potsdam. "He is straightforward." This gave Stalin the breathing time he needed to solidify his hold on Eastern Europe.

The next year, Truman's mother played a role in turning the president, writing to him that it was time "to get tough with someone," according to Greg Behrman, author of "The Most Noble Adventure," a chronicle of the Marshall Plan.

'Iron Curtain'

Winston Churchill helped, too. In his "Iron Curtain" speech, the out-of-office Churchill poured out the wisdom of his experience, concluding that "from Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the continent." The speech bespoke his despair at not stopping Stalin at Yalta.

There are also, of course, presidents who never get to even Hillary's point on the curve. One of them, we now know, was Richard Nixon. By going to China, Nixon the Republican rendered anyone who supported a diplomatic boycott of Beijing extreme. He and Henry Kissinger created a new vocabulary of acceptance: dictators were "leaders," not tyrants. China was inviting, not "red."

'Jovial' Zhou

An entire generation grew up reading about the charms of the diplomatic dance with Beijing. That same generation learned all about the skilled premier, Zhou Enlai.

"Relaxed and jovial," read the first few lines about Zhou in a typical 1970s news story. Kissinger expressed an almost Obama-ish enthusiasm when it came to the Chinese official: "My extensive discussions with Zhou in particular," he wrote to Nixon, "had all the flavor, texture, variety and delicacy of a Chinese banquet."

What this picture omitted was that Zhou was more lackey than premier in the "Nixon Goes to China" period. As Jung Chang and Jon Halliday point out in a damning biography of Mao, Mao kept Zhou in line by humiliating him in big and small ways — forcing him to sit on a hard chair in a meeting with the Nepalese king, when he knew Zhou had bladder cancer, for example.

One way Mao managed Zhou's management of Kissinger was by withholding medical treatment for that cancer. Only after an especially spectacular success with Kissinger in February of 1973 did Mao allow Zhou to get his surgery — and then only a partial removal of the disease. Such recent revelations cast new light on Nixon's decision to go to China.

Legitimate Grudge

It will probably be awhile before we get the papers on Iranian President Mahmoud Ahmadinejad or the details on Zimbabwean leader Robert Mugabe. But the European foreign ministers who met with the Iranian leader so readily in the months after his election in 2005 are likely to rue their decision. The same may hold for President George W. Bush and his special relationship with Vladimir Putin.

A good share of anti-Americanism across the globe is pointless or worse. The Democrats who mutter on about it from Iowa to November 2008 will mostly be wrong.

But there is one grudge against the U.S. that is legitimate. It's that the very freshness that ensures presidential electability — Obama's sudden rock star quality — makes for especially costly foreign policy leadership.

The ease with which U.S. politicians are distracted by secondary issues is also infuriating — the fight over Mitt Romney's Mormonism. Israelis, Zimbabweans, Sudanese, Iranians — all will watch as the next president climbs the curve. That president may get to wisdom, but for many of those who watch, the recognition will come too late.

(Amity Shlaes, a senior fellow at the Council on Foreign Relations in economic history, is a Bloomberg News columnist. The opinions expressed are her own.